// Copyright (C) 2020 THL A29 Limited, a Tencent company.  All rights reserved.
// Please refer to the license text that comes with this tendis open source
// project for additional information.

/*
 * Copyright (c) 2000-2010 Marc Alexander Lehmann <schmorp@schmorp.de>
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

#include "tendisplus/utils/redis_port.h"
#include "lzfP.h"

namespace tendisplus {
namespace redis_port {
#if AVOID_ERRNO
#define SET_ERRNO(n)
#else

#include <errno.h>

#define SET_ERRNO(n) errno = (n)
#endif

#if USE_REP_MOVSB /* small win on amd, big loss on intel */
#if (__i386 || __amd64) && __GNUC__ >= 3
#define lzf_movsb(dst, src, len)        \
  asm("rep movsb"                       \
      : "=D"(dst), "=S"(src), "=c"(len) \
      : "0"(dst), "1"(src), "2"(len));
#endif
#endif

unsigned int lzf_decompress(const void* const in_data,
                            unsigned int in_len,
                            void* out_data,
                            unsigned int out_len) {
  u8 const* ip = (const u8*)in_data;
  u8* op = reinterpret_cast<u8*>(out_data);
  u8 const* const in_end = ip + in_len;
  u8* const out_end = op + out_len;

  do {
    unsigned int ctrl = *ip++;
    // literal run
    if (ctrl < (1 << 5)) {
      ctrl++;

      if (op + ctrl > out_end) {
        SET_ERRNO(E2BIG);
        return 0;
      }

#if CHECK_INPUT
      if (ip + ctrl > in_end) {
        SET_ERRNO(EINVAL);
        return 0;
      }
#endif

#ifdef lzf_movsb
      lzf_movsb(op, ip, ctrl);
#else
      switch (ctrl) {
        case 32:
          *op++ = *ip++;
        case 31:
          *op++ = *ip++;
        case 30:
          *op++ = *ip++;
        case 29:
          *op++ = *ip++;
        case 28:
          *op++ = *ip++;
        case 27:
          *op++ = *ip++;
        case 26:
          *op++ = *ip++;
        case 25:
          *op++ = *ip++;
        case 24:
          *op++ = *ip++;
        case 23:
          *op++ = *ip++;
        case 22:
          *op++ = *ip++;
        case 21:
          *op++ = *ip++;
        case 20:
          *op++ = *ip++;
        case 19:
          *op++ = *ip++;
        case 18:
          *op++ = *ip++;
        case 17:
          *op++ = *ip++;
        case 16:
          *op++ = *ip++;
        case 15:
          *op++ = *ip++;
        case 14:
          *op++ = *ip++;
        case 13:
          *op++ = *ip++;
        case 12:
          *op++ = *ip++;
        case 11:
          *op++ = *ip++;
        case 10:
          *op++ = *ip++;
        case 9:
          *op++ = *ip++;
        case 8:
          *op++ = *ip++;
        case 7:
          *op++ = *ip++;
        case 6:
          *op++ = *ip++;
        case 5:
          *op++ = *ip++;
        case 4:
          *op++ = *ip++;
        case 3:
          *op++ = *ip++;
        case 2:
          *op++ = *ip++;
        case 1:
          *op++ = *ip++;
      }
#endif
    } else {  // back reference
      unsigned int len = ctrl >> 5;

      u8* ref = op - ((ctrl & 0x1f) << 8) - 1;

#if CHECK_INPUT
      if (ip >= in_end) {
        SET_ERRNO(EINVAL);
        return 0;
      }
#endif
      if (len == 7) {
        len += *ip++;
#if CHECK_INPUT
        if (ip >= in_end) {
          SET_ERRNO(EINVAL);
          return 0;
        }
#endif
      }

      ref -= *ip++;

      if (op + len + 2 > out_end) {
        SET_ERRNO(E2BIG);
        return 0;
      }

      if (ref < reinterpret_cast<u8*>(out_data)) {
        SET_ERRNO(EINVAL);
        return 0;
      }

#ifdef lzf_movsb
      len += 2;
      lzf_movsb(op, ref, len);
#else
      switch (len) {
        default:
          len += 2;

          if (op >= ref + len) {
            /* disjunct areas */
            memcpy(op, ref, len);
            op += len;
          } else {
            /* overlapping, use octte by octte copying */
            do {
              *op++ = *ref++;
            } while (--len);
          }

          break;

        case 9:
          *op++ = *ref++;
        case 8:
          *op++ = *ref++;
        case 7:
          *op++ = *ref++;
        case 6:
          *op++ = *ref++;
        case 5:
          *op++ = *ref++;
        case 4:
          *op++ = *ref++;
        case 3:
          *op++ = *ref++;
        case 2:
          *op++ = *ref++;
        case 1:
          *op++ = *ref++;
        case 0:
          *op++ = *ref++; /* two octets more */
          *op++ = *ref++;
      }
#endif
    }
  } while (ip < in_end);

  return op - reinterpret_cast<u8*>(out_data);
}
}  // namespace redis_port
}  // namespace tendisplus
